Queen Mary could operate naturally with the Lions at about 28 knots while carrying roughly 510 additional tons at nearly the same dimensions. She was only about an inch longer, slightly wider, and an inch shallower at deep load, so the added displacement did not come from a radically larger hull. Her plant used 42 Yarrow boilers and Parsons direct-drive turbines for about 75,000 shaft horsepower, with cruising arrangements for economy. Her sixteen 4-inch guns were arranged differently from those in the Lions, another incremental change within the same basic design family. The measurements and machinery give specific meaning to the description "improved Lion."
Chapter · 27:03-30:54
Queen Mary's machinery and Lion-family dimensions
Queen Mary's near-Lion dimensions, greater displacement, machinery, and armament arrangement show that she was a heavier refinement of the same design.